Life-cycle GHG emissions per MJ of fuel produced and combusted for both 100-year and 20-year time horizons. Gasoline section shows results for fuel derived from both conventional oil and oil sands. Expansion bars show the components of fuel production. Credit: ACS, Burnham et al. Click to enlarge.

The base results from a study by a team at the Center for Transportation Research, Argonne National Laboratory indicate that shale gas life-cycle greenhouse gas (GHG) emissions are 6% lower than conventional natural gas, 23% lower than gasoline, and 33% lower than coal. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty whether shale gas emissions are actually lower than those of conventional natural gas.

The study also highlights that upstream CH4 (methane) leakage and venting is a key contributor to the total upstream emissions of natural gas pathways, and can significantly reduce the life-cycle benefit of natural gas compared to coal or petroleum. The study found that shale gas (SG) well completion and workover emissions are a much more significant factor as compared to a conventional natural gas (NG) pathway. The study is published in the ACS journal Environmental Science & Technology.

In the United States, there has been a rapid increase in natural gas (NG) production from shale formations due to recent advancements in drilling technologies, such as horizontal drilling and hydraulic fracturing. In horizontal drilling, a well is drilled down to the depth of the play and turned approximately 90 degrees to run laterally through the formation. This allows for greater access to the play and can increase production on a per-well basis. Due to the low permeability of shale, producers hydraulically fracture the formation to enable better flow of NG. The fracture fluid is typically water-based and contains proppants to maintain fracture openings once pumping of the fluid has ceased. The development of this resource has generated interest in expanding NG usage in areas such as electricity generation and transportation. However, the environmental impacts (e.g., water quality, air quality, global climate change) of shale gas (SG) production and use are currently being debated as the impacts of these new technologies have just started to be examined.

...In this analysis we examined the current state of knowledge regarding the key CH4 emission sources from shale gas, conventional NG, coal, and petroleum to estimate up-to-date GHG emissions and to understand the uncertainties involved in calculating their life-cycle GHG impacts. We used the GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) model, which can analyze more than 100 fuel pathways, to perform our simulations. We updated the latest version, GREET 1.8d, to include shale gas production and have revised the existing pathways for NG, coal, and petroleum. Through this effort we have also identified data gaps that need to be addressed in future GHG assessments of the natural gas life cycle.

—Burnham et al.

The Argonne-developed GREET is widely used to examine life-cycle energy and emission effects of different transportation fuels and advanced vehicle technologies. The Argonne team here used GREET to estimate the GHG emissions from feedstock recovery, fuel production, and fuel use as well as from transportation and distribution of feedstocks and fuels.

In this study, they expanded the system boundary to include infrastructure establishment, including gas well drilling and completion. The GREET model calculates CO2, CH4, and N2O emissions for each stage from both fuel combustion and non-combustion sources such as leaks.

Based on the findings, the team emphasized the volume of gas vented during completions and workovers of shale gas wells needs to be examined with and without technologies and practices that can reduce emissions. This, in turn will require a better understanding of the volumes of both fracking fluids and natural gas being released during the flowback and how those volumes vary during the process, they said.

They also suggested that:

The number of workovers typically performed during the lifetime of shale gas wells needs further examination as the decision to do a workover will be based on the economics of the well, likely depending on factors such as the age of the well, expected improvement in production after workover, and the wellhead price of NG.

Greater transparency is needed on the percentage of completions and workovers implementing REC (reduced emissions completion) technologies. A survey of flaring practices for wells with and without RECs by examining state regulations and industry practices would provide greater certainty of the emissions from shale gas.

For conventional wells, the volume of gas vented during liquid unloadings (removing liquids that gradually build up and block flow in wet gas wells) needs to be calculated for the various technologies implemented to removing liquids, along with a survey of the prevalence of each technology in practice would provide much greater certainty to these emissions. This survey should also examine the percentage of conventional NG and shale wells requiring liquid unloadings as not all wells undergo this process.

The number of unloadings required over the lifetime of a well is a factor that causes significant uncertainty and should be examined in detail. This data should differentiate the unloadings required in different basins/geologic formations as well as in different wells within the same basin. The number of unloadings required as function of the age of the well would also provide relevant information when trying to create an inventory of these emissions.

Flaring practices should also be examined for liquid unloading operations by examining state regulations and industry practices.

Large-scale shale gas production is a relatively new phenomenon. Environmental management in general and GHG emission reduction in particular need to be exercised in order for shale gas (and conventional NG) to be produced sustainably. The partnership of the natural gas industry and EPA under the NG STAR program has helped reduce CH4 emissions but further efforts could be taken to address remaining environmental issues of natural gas production and transmission. With this context, our analysis, among other analyses, provides some insight on critical stages that industry and government agencies could work together on to reduce the environmental footprint of natural gas.

Comments

HarveyD
Without (yet) having read the report, I might agree with you on a principal level (excluding the comment on corruption) but I still have a couple of questions: How do you know that? What is your reference? Have you published anything in this field yourself?

It is becoming well known that data about GHG and pollution from SG operations is rarely complete. SG leaks are more numerous than reported. Pollution related to all SG operations, specially the multiple chemicals used is often kept secret, minimized and/or overlooked. Our specialized 50-member team has not managed to evaluate the total impact after one full year.

The answer to your question is that nobody really has the total picture yet. The industry (who certainly knows more) is not collaborating much and is more often trying to mislead the investigation team, much like tobacco firms did for decades. It is no where as clean as the industry says it is.

By incomplete-missing-corrupted data...I did not mean corrupted people but in that field too one many find a few, specially the communication specialists giving out questionable information.

@HarveyD
I have not met anyone but Michael Wang from the list of authors. However, I would regard him as a very thorough and careful scientist and all publications in the past from this team support this conclusion. In general, this is perhaps the number one group of scientists you have in this field in the USA. I doubt that they would be easily misled by the industry. In addition, the GREET database has been subject to independent evaluation through several peer-reviewed publications. This is also the case with the paper in EST. Maybe there is a lack of data but at least, I am convinced that the authors have tried to make a “best guess”. On the contrary, I am quite disturbed by your way of spreading ill-founded and malignant comments on this forum. Very, very seldom do you present any data to support your comments and accusations. Neither did you this time.

Peter_XX...it is a well known secret that Oil & Gas Cos have managed to hide valuable and pertinent information from the public for many decades. I recently visited Baku City and I was surprised to see many square miles of abandoned rusty old Oil pumps and rusted leaking pipelines at the city door steps. The grounds have not been cleaned and nothing grows there for the last 100+ years. The smell of crude is still very present even after all operations have ceased for many decades. The Noble Brothers (the first operators) would not be very proud of what they have left behind.

Our SG investigating team have spent many days in Pennsylvania and is not very pleased with what they have seen, heard, smelled and with water, ground and air samples brought back for further analyses. Their final reports will probably be delayed by legal actions from interested parties.

Will current SG operators repair the multiple damages done with the same effectiveness (read disregards) as was done in Baku?

There is no doubt that energy companies have taken the quick route many times in past shale plays, and they'll continue to do so until regulations/public perception force their hand.

Nevertheless, there have been numerous independent studies now that have suggested that fracking natural gas, for instance, can be environmentally safe while reducing CO2 emissions. Of course, this requires extra costs in the development of these resources -- perhaps making them less enticing compared to alternatives.

However, the implication -- which you seem to be making -- that natural gas and shale are simply forever more environmentally dangerous compared to petroleum resources, for instance, seems impossible to prove based upon today's available science.

Moreover, if lithium, for instance, were judged by the historical pollution caused by its development thus far as a resource, one could use your same logic and claim that lithium is an environmentally dangerous resource, as there has been well documented cases of extreme pollution thus far.

Fortunately, both of these resources can be developed in much cleaner ways.

In my opinion, fracking is inevitable. Eventually, even if only just for a short while, Iran is going to make travel through the Straits of Hormuz difficult, if not impossible. And once gas prices double permanently, I'm quite confident voters will demand that cheaper and domestic natural gas be utilized. Besides, today cheap energy easily trumps pollution as an American concern.

Consequently, in my opinion, the anti-fracking/natural gas crowd isn't just fighting a losing battle, they are making the situation far worse than it needs to be.

Fracking should be seen as the impetus to compromise. Fracking today in exchange for a greater focus on fuel economy and the development of more sustainable resources as we head into the future. The goal of the sustainable crowd should be to ensure that nat gas is simply a step to greater sustainability.

That may be the core of the long term problem. Whenever a nation puts cheap energy, easy profits and re-election of its leaders ahead of environmental and health concerns, it becomes an unsustainable way of life.

There is nothing basically wrong with mining, fracking, oil wells, gas wells etc as long as it is done in such ways as to protect the environment and health of living creatures. Unfortunately, that has not always been the case. The opposite is too often the rule. That is where governments have to be more pro-active and not give up so quickly for electoral reasons.

By the way, I do not favour crude oil over NG/SG and/or alternative fuels. I'm very pro electrification from clean current and future electricity sources. Improved energy savings should become part of our culture.

Energy savings is what RMI calls "negawatts" which can be the most cost effective first steps. The Keystone XL pipeline has more to do with the refining companies sending product out of the U.S. for profit than for affordable fuel here in the U.S.

Three fundamental words come to mind when considering the failure of certain environmental goals:

Exaggeration
Hyperbole
Catastrophizing

Harvey tends to use these fundamentals. The thought is based on out-dated psychology, believing that fear-based catastrophe is the only way to capture public attention. While this has proved true in the short term, we are seeing in the long term its extreme fragility.

Take for example two enviro protocols, Kyoto meant to address Anthro Global Warming, and Montreal meant to eliminate the Antarctic ozone loss. Both have failed in part because their catastrophic promises never materialized. Incidence of UV-B skin cancer is no greater today than 30 years ago, and ozone losses have actually grown. And Durban confirms how claims of rising seas, cataclysmic melting, and anomalous weather caused by CO2, has fared with the general public. Fear-based campaigns do not work.

There is now a very progressive movement to present environmental concerns with far less hysteria. It is effective. This does not give energy companies a free pass. Energy/resource exploitation of any kind demands restorative cleanup. Recycling is working and must continue. Natural resources need stewardship. And CONSERVATION is the socio-political process we use to preserve pristine wilderness and habitat.

We are approaching a time when even natural gas will become unnecessary. Clean energy is abundant and we are learning to use it. Until then, using cleaner fossil resources that reduce our demand for oil and coal makes good financial and environmental sense.

Yes, a squandering throw away society is difficult to change, short of a deep enough convincing financial recession, in the making. Snow balling consumption keeps the economy going but has its limits. Its like gaining weight. After 600+ lbs, it gets difficult to add more on the human body.

Reel$$...you may or may not know that over 2800 sugar cane workers die every year in Central America from Chronic Kidney Disease (CKD). The number of workers affected increased 500% in the last 20 years and corresponds with a five fold increase in sugar cane crop due to higher demand for (clean) ethanol exported to USA.

Alternative fuels may not be all that environmentally friendly nor very healthy for many directly involved with the associated processes.

If you know a cure for CKD many thousand widows and orphans would appreciate it. If not, it may become as much a killer as recent oil wars.

According to projections, you might be waiting until 2050 for those 100 million EVs. Since peak oil may have already occurred, with India and China driving more cars, we may need a plan that is a bit more effective in the near term.